Analysis of impurities in NaPF6 for sodium-ion batteries by inductively coupled plasma tandem mass spectrometry

To detect metal impurities in the electrolyte of sodium-ion batteries (sodium hexafluorophosphate, NaPF₆) and ensure the performance stability and safety of sodium-ion batteries, a new strategy for identifying detrimental metal impurities is proposed. In this work, inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) was used to study 12 metal impurities in NaPF₆. The NaPF₆ sample was dissolved in ultra-pure water and directly analyzed by ICP-MS/MS, and the spectral interference was eliminated by the reaction gas mixture N₂O/H₂ in the MS/MS mode. The analysis results were compared with the results from sector field (SF)-ICP-MS, and the accuracy and reliability of the developed method were evaluated by a spike recovery test. Under optimized conditions, the limit of detection (LOD) of analytes was in the range of 0.16–3.2 ng L⁻¹, the spiked recovery was in the range of 94.4 %–105 %, and the relative standard deviation (RSD) was 1.3 %–4.1 %. Statistical analysis showed that, at the confidence level of 95 %, there was no significant difference between the analysis results from the developed method and SF-ICP-MS. The developed method is accurate and reliable, with good stability and high accuracy. The ICP-MS/MS method based on the N₂O/H₂ reaction mode shows strong potential for analyzing various metal impurities in NaPF₆, and can be extended to other fields with great reference value.